Why does bromelin in uncooked pineapple juice keep gelatin from solidifying?

Bromelain is an enzyme found in uncooked PineApple Juice that breaks down proteins. When Gelatin is mixed with pineApple juice, bromelain digests the proteins in the gelatin, preventing it from forming the gel structure necessary for solidification. This interference with the protein bonding process is why gelatin fails to set when combined with fresh pineApple juice. Cooking the pineApple destroys the bromelain, allowing gelatin to solidify properly.